The invention relates to a method and an apparatus for producing shock waves for medical applications.
For various medical indications, shock waves are used that are produced in a fluid volume and focused on the areas of the patient to be treated. Various methods and apparatuses are known for producing the shock waves.
In one embodiment, the shock waves are produced by electromagnetic means. An electrical impulse in a coil is used to a deflect a diaphragm by producing a pressure pulse in the adjacent fluid volume. If the coil is a flat coil, this produces an even pressure wave, which is focused by means of acoustic lenses located in the fluid volume. If the coil and the membrane are curved, then the pressure wave that is produced is focused by the curved diaphragm surface. If a cylindrical coil is used, the cylindrically expanding pressure wave is reflected and focused by a correspondingly shaped rotation surface.
A further known method for producing the pressure waves is to use piezoelectric elements. The piezoelectric elements can be located on a rotation surface, so that pressure waves produced by these elements are focused.
Finally, a method is known to produce the shock waves by electro hydraulic means. In this process, an electric spark discharge is ignited in the fluid volume, which produces a plasma bubble. The shock wave, which expands spherically, is focused by reflecting on suitable rotation surfaces.
In all of these known methods, the shock wave is triggered by an electrical impulse. The required electrical impulses generally are characterized by short rise times and high energy, so that electromagnetic shielding problems arise, which can have adverse effects, especially in the presence of further electrical devices or patient-related apparatuses e.g. pacemakers. Some of the known devices also display high electrical power dissipation, which necessitates expensive cooling systems. Consequently, there exist an unfulfilled need for a method and an apparatus for producing shock waves for medical application, which ensures better degree of efficiency and less electromagnetic shielding problems.